Lift type weight measuring apparatus

ABSTRACT

The present invention provides a lift type weight measuring apparatus ( 400 ) which is able to measure the weight of a measurement object after spatially isolating the measurement object. The lift type weight measuring apparatus ( 400 ) includes an upper sensing plate ( 410 ) to move upwards, and weight sensing means provided under the upper sensing plate ( 410 ) to sense a weight of the measurement object seated on the upper sensing plate. The lift type weight measuring apparatus ( 400 ) further includes lift means to move both the upper sensing plate and the weight sensing means vertically, and control means to control the operation of the lift means and to measure the weight of the measurement object using a weight sensing signal output from the weight sensing means.

TECHNICAL FIELD

The present invention relates, in general, to lift type weight measuringapparatuses and, more particularly, to a lift type weight measuringapparatus which is able to measure the weight of measurement objectafter spatially isolating the measurement object from a main body.

BACKGROUND ART

Generally, centrifuges are apparatuses in which a rotor holding abucket, in which a sample is placed, is rotated at high speed to applyhigh centrifugal force to the sample, so that a high density fraction ismoved radially outwards and a low density fraction is moved radiallyinwards, thus separating the fractions from each other.

FIG. 1 is a perspective view showing a conventional automatic balancingcentrifuge. As shown in FIG. 1, the automatic balancing centrifugeincludes a base 110, a centrifugal motor 120 which is supported by thebase 110, a rotor 130 which is coaxially coupled to the centrifugalmotor 120 and has a rotor lever 160, and a bucket 140 which has apredetermined volume to contain therein a desired sample 150 to beseparated into fractions. The rotor 130 is provided with an upperhousing 172 having a cubic cap shape and a lower housing 174 in whichone rotor lever 160 is mounted. The rotor lever 160 has a lever centralbody 161 which is positioned at the center of the rotor lever 160, andtwo rotating arms 162 which are coupled at opposite ends of the levercentral body 161 by hinges 163, thus being rotatable vertically. Apressure sensor 168 is mounted on a lower portion of each of therotating arms 162 provided at the opposite ends of the lever centralbody 161, so as to directly sense the pressure of the rotating arm 162.The rotating arms 162 are balanced by the support of the pressuresensors 168. Two lever guide holes 166 are provided at opposite sides onouter surfaces of the upper and lower housings 172 and 174. The rotorlever 160 is inserted through the lever guide holes 166 and ishorizontally movable in the lever guide holes 166 to maintain balance.In the drawings, the reference numeral 164 denotes a stop protrusionwhich is provided on each inner surface of the rotating arms 162 to holdthe bucket 140. The reference numeral 142 denotes a stop groove which isformed on the bucket 140 to engage with the stop protrusion 164. In thisconstruction, when measuring values of the opposite pressure sensors 168are different in the state in which the samples 150 are placed in thebuckets 140, a lever moving motor 182 provided in the upper housing 172is operated. Then, the rotor lever 160 is horizontally moved by theoperation of the lever moving motor 182, thus becoming balanced.

According to such a conventional automatic balancing centrifuge,imbalance of samples supported by the rotor lever is sensed prior toevery centrifugal operation and, thereafter, the rotor lever is movedaccording to the imbalance sensing result, thus automatically balancingthe centrifuge. Therefore, the samples are prevented from damage due toimbalance of the rotor and, as well, the lifetime of the automaticbalancing centrifuge is extended. However, the conventional automaticbalancing centrifuge is problematic in that because the weight sensorsuch as the pressure sensors are frequently struck by the bucketscontaining the measurement objects, the weight sensor is easily damaged.

DISCLOSURE OF INVENTION Technical Problem

Accordingly, the present invention has been made keeping in mind theabove problems occurring in the prior an, and an object of the presentinvention is to provide a lift type weight measuring apparatus which hasa structure capable of separating a weight sensor from a measurementobject so that the weight sensor is prevented from damage due tofrequent contact between the weight sensor and the measurement object.

Technical Solution

In order to accomplish the above object, the present invention providesa lift type weight measuring apparatus, including: an upper sensingplate to move upwards, thus spatially isolating a measurement object; aweight sensing means provided under the upper sensing plate to sense aweight of the measurement object seated on the upper sensing plate; alift means to move both the upper sensing plate and the weight sensingmeans vertically; and a control means to control an operation of thelift means and to measure the weight of the measurement object using aweight sensing signal output from the weight sensing means.

ADVANTAGEOUS EFFECTS

In the present invention, a lift type weight measuring apparatus is ableto separate a weight sensor from a measurement object, so that theweight sensor is prevented from damage due to frequent contact betweenthe weight sensor and the measurement object.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing a conventional automatic balancingcentrifuge;

FIG. 2 is a sectional view of a rotor of the automatic balancingcentrifuge taken along the line A-A of FIG. 1;

FIG. 3 is a perspective view of an automatic balancing centrifuge havinga lift type weight measuring apparatus according to an embodiment of thepresent invention;

FIG. 4 is a perspective view showing an enlargement of the lift typeweight measuring apparatus of FIG. 3;

FIG. 5 is a sectional view taken along the line C-C of FIG. 4;

FIG. 6 a is a sectional view showing the relationship between a stopprotrusion of a rotating aim and a stop groove of a bucket of FIG. 3before a weight measurement;

FIG. 6 b is a sectional view showing the relationship between the stopprotrusion of the rotating arm and the stop groove of the bucket of FIG.3 during the weight measurement;

FIG. 7 is an electrical block diagram of the lift type weight measuringapparatus of the present invention;

FIG. 8 a is a sectional view taken along the line B-B of FIG. 3 to showa state of the lift type weight measuring apparatus before the weightmeasurement; and

FIG. 8 b is a sectional view taken along the line B-B of FIG. 3 to showa state of the lift type weight measuring apparatus during the weightmeasurement.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, a lift type weight measuring apparatus according to apreferred embodiment of the present invention will be described indetail with reference to the attached drawings.

Mode for the Invention

Implementation in an automatic balancing centrifuge will be explained asan example.

FIG. 3 is a perspective view of an automatic balancing centrifuge havinga lift type weight measuring apparatus according to an embodiment of thepresent invention FIG. 6 a is a sectional view showing the relationshipbetween a stop protrusion of a rotating arm and a stop groove of abucket of FIG. 3 before a weight measurement FIG. 6 b is a sectionalview showing the relationship between the stop protrusion of therotating arm and the stop groove of the bucket of FIG. 3 during theweight measurement. As shown in FIG. 3, the automatic balancingcentrifuge includes a base 310 on which every component is loaded, amotor support plate 320 which is mounted on the base 310, and acentrifugal motor 322 which is supported by the motor support plate 320.The automatic balancing centrifuge further includes a rotor 330 which isprovided with a rotor lever 340 and which is coaxially coupled to thecentrifugal motor 322, and a pair of buckets 360 containing thereinsamples to be separated into fractions. The rotor 330 may have the sameconstruction as that of the above-mentioned conventional automaticbalancing centrifuge. Each bucket 360 containing the sample has a pairof stop grooves 362. Thus, when each bucket 360 is coupled to each of aplurality of rotating arms 342, the stop grooves 362 of the bucket 360engage with a pair of stop protrusions 344 of each rotating arm 342, sothat the bucket 360 is reliably supported by the rotating arm 342. Here,because the stop protrusions 344 must not interference with each bucket360 being weighed, each stop groove 362 of each bucket 360 mustgradually enlarge in width and depth from top to bottom. In thedrawings, the reference numeral 350 denotes a motor shaft which couplesthe centrifugal motor 320 to the rotor 330. The reference numeral 400denotes the lift type weight measuring apparatus of the presentinvention which is mounted on the base 310 of the centrifuge.

FIG. 4 is a perspective view showing an enlargement of the lift typeweight measuring apparatus of FIG. 3. FIG. 5 is a sectional view takenalong the line C-C of FIG. 4. As shown in FIGS. 4 and 5, the lift typeweight measuring apparatus 400 includes a vertical frame 440 to whichboth an upper horizontal frame plate 440 and a lower horizontal frameplate 444 are fastened. The weight measuring apparatus 400 furtherincludes a lift drive motor 432 which is fastened to the lowerhorizontal frame plate 444, and a rotating shaft 434 which is axiallycoupled to the lift drive motor 432 and, thus, is rotated by theoperation of the lift drive motor 432. The weight measuring apparatus400 further includes a central slide 436 which is screwed to therotating shaft 434 to convert the rotation of the lift drive motor 432into vertical linear movement. The weight measuring apparatus 400further includes an upper sensing plate 410 on which the bucket 360 isseated, and a weight sensor 422 which is coupled to a lower surface ofthe upper sensing plate 410 by a locking bolt to measure the weight ofthe bucket 360. The weight measuring apparatus 400 further includes alower sensing plate 421 which is coupled to a lower end of the weightsensor 422 by a locking bolt and which is coupled to an upper end of thecentral slide 436. The weight measuring apparatus 400 further includesat least one guide 426 which is coupled to the upper horizontal frameplate 442 to help the lower sensing plate 421 correctly move verticallywithout shaking.

Preferably, the weight measuring apparatus 400 further includes a linearbush 424 to reduce friction between the guide 426 and the lower sensingplate 421 during the vertical movement of the lower sensing plate 421 bythe operation of the lift drive motor 432. Furthermore, it is preferredthat the weight measuring apparatus 400 include a position sensor 454 tocorrectly stop the upper sensing plate 410 at its desired higher orlower position. The position sensor 454 is supported by a positionsensor support 452 which is coupled to the lower sensing plate 421. Alight emitting device 454 b is provided on a side of the position sensor454. A light receiving device 454 a is provided on the other side of theposition sensor 454 to receive light emitted from the light emittingdevice 454 b. Thus, the position sensor 454 senses a mark formed on aposition sensing panel 456 which is attached to the upper horizontalframe plate 442. In detail, upper and lower light openings 456 b and 456a are respectively formed at predetermined higher and lower positions onthe position sensing panel 456.

In the meantime, the weight sensor 422 is embodied by a device, such asa strain gauge, piezoelectric sensor, etc. The position sensor 454 isvariously embodied by a device, such as an interrupt type photocoupler,or a switch, etc. Furthermore, a metal lubricant may be used in place ofthe linear bush 424. It is preferred to use a stepping motor as the liftdrive motor 432.

FIG. 7 is an electrical block diagram of the lift type weight measuringapparatus of the present invention. As shown in FIG. 7, an electricalconstruction of the lift type weight measuring apparatus of the presentinvention includes a position sensing unit 730 which is provided withboth the position sensor 454 and its peripheral devices, and a weightsensing unit 720 which is the weight sensor 422 and its peripheraldevices. The electrical construction of the lift type weight measuringapparatus further includes a key input unit 710 which is required toinput various keys necessary for the weight measurement and a displayunit 740 which displays various kinds of information about the operationof the weight measuring apparatus. The electrical construction of thelift type weight measuring apparatus further includes a sensor movingunit 750 which vertically moves the upper sensing plate 410 using thelift drive motor 432, and a control unit 700 which control the operationof the entire apparatus.

FIG. 8 a is a sectional view of a part of the centrifuge taken along theline B-B of FIG. 3, in which the bucket 360 having therein a sample tobe separated is not lifted. Every rotating arm 342 of the centrifuge iscontrolled by the movement of the rotor lever 340, such that therotating arms 342 are in the same rotating track around the rotor 330.One rotating arm 342 is placed at a predetermined position over theweight measuring apparatus 400 by the operation of both the centrifugalmotor 322 and a constant position sensor (not shown). At this time, apredetermined space must exist between the bucket 360 containing thesample and the upper sensing plate 410 to allow spatial variation in therotating track of the bucket 360 due to centrifugal force during therotation of the rotor lever 340.

FIG. 8 b is a sectional view taken along the line B-B of FIG. 3 to showa state of the lift type weight measuring apparatus during the weightmeasurement. In the state of FIG. 8 a, the lift drive motor 432 isoperated to measure the weight of the bucket 360 and lifts the lowersensing plate 421 upwards. At this time, the lift drive motor 432 isoperated until the bucket 360, which is raised by the upper sensingplate 410, is placed at a predetermined position at which the bucket 360does not interfere with its peripheral component, that is, the stopprotrusions 344. This position can be determined by the position sensor454 which senses the upper light opening 456 b of the position sensingpanel 456. The position signal sensed through the above-mentionedprocess is sent to the control unit 700. The control unit 700 gives acontrol command to the sensor moving unit 750, so that the rotation ofthe lift drive motor 432 is stopped. In this state, the weight sensingunit 720 senses the weight of the bucket 360 and transmits this weightsensing signal to the control unit 700. Then, the control unit 700temporarily stores the weight sensing signal and transmits it to a maincontroller (not shown) of the centrifuge. Thereafter, the control unit700 outputs a control signal to the sensor moving unit 750 to reverselyrotate the lift drive motor 432, thus moving the lower sensing plate 421downwards. In the downward movement of the lower sensing plate 421, theposition sensor 454 moves downwards along with the lower sensing plate421 and senses the lower light opening 456 a formed at the lowerposition on the position sensing panel 456. Thereafter, this sensingsignal is sent to the control unit 700. Then, the control unit 700 givesa control command to the sensor moving unit 750 so that the rotation ofthe lift drive motor 432 stops. At this time, the stop grooves 362 ofthe bucket 360 engage with the stop protrusions 344 of the rotating arm342 again. The rotor 330 becomes rotatable. Next, the control unit 700transmits the result of the measured weight of the relevant bucket 360to the main controller of the centrifuge. The main controller of thecentrifuge rotates the rotating arms 342 to 180 degrees to measure theweight of the other bucket 360 which is hung on the other rotating arm342. Thereafter, the main controller notifies the control unit 700.Then, the control unit 700 measures the weight of the relevant bucket360 through the above-mentioned weight measuring process and transmitsthe result to the main controller. According to the result, the maincontroller moves the rotor lever 340 horizontally to balance therotating arms 342 and, thereafter, executes a centrifugal process.

The lift type weight measuring apparatus of the present invention is notlimited to the above-mentioned embodiment, and various modifications arepossible, without departing from the scope and spirit of the presentinvention. That is, in this specification, the example in which the lifttype weight measuring apparatus is used in an automatic balancingcentrifuge has been explained, but it can be used in other apparatuses.

1. A centrifuge, comprising: a centrifugal motor; a rotor coupled to anoutput shaft of the centrifugal motor; and a rotor lever mounted to therotor to rotatably support a bucket containing a sample therein, whereinthe centrifuge further comprises: an upper sensing plate provided belowa rotating track of the bucket, the upper sensing plate moving upwardsto spatially isolate the bucket; weight sensing means provided under theupper sensing plate to sense a weight of the bucket seated on the uppersensing plate; position sensing means to sense a predetermined highposition and a predetermined low position of the upper sensing plate;lift means to move both the upper sensing plate and the weight sensingmeans vertically; and control means to control an operation of thecentrifugal motor, to control the lift means using a signal output fromthe position sensing means, and to determine the weight of the bucketusing a signal output from the weight sensing means.
 2. The centrifugeaccording to claim 1, further comprising: lift guide means to guidevertical movement of the lift means.
 3. (canceled)